A substance found in most tissues in the body, and in many foods. It can also be made in the laboratory. It is used by the body to produce energy for cells, and as an antioxidant. It is being studied in the treatment of cancer and in the relief of side effects caused by some cancer treatments. Also called coenzyme Q10, Q10, CoQ10, and vitamin Q10.

UCN-01

An anticancer drug that belongs to the family of drugs called staurosporine analogs.

UGT1A1

A substance that is being studied as a treatment for cancer. It is an enzyme produced by the liver and intestine.

ulcer (UHL-ser)

A break on the skin, in the lining of an organ, or on the surface of a tissue. An ulcer forms when the surface cells become inflamed, die, and are shed. Ulcers may be linked to cancer and other diseases.

ulceration

The formation of a break on the skin or on the surface of an organ. An ulcer forms when the surface cells die and are cast off. Ulcers may be associated with cancer and other diseases.

ulcerative colitis

Chronic inflammation of the colon that produces ulcers in its lining. This condition is marked by abdominal pain, cramps, and loose discharges of pus, blood, and mucus from the bowel.

Ulmus fulva

Ulmus rubra. The inner bark of this plant has been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called slippery elm, gray elm, Indian elm, red elm, and sweet elm.

Ulmus rubra

Ulmus fulva. The inner bark of this plant has been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called slippery elm, gray elm, Indian elm, red elm, and sweet elm.

ultrasonogram

A computer picture of areas inside the body created by bouncing high-energy sound waves (ultrasound) off internal tissues or organs. Also called a sonogram.

ultrasonography (UL-tra-son-OG-ra-fee)

A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasound.

ultrasound

A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasonography.

ultrasound energy

A form of therapy being studied as an anticancer treatment. Intensified ultrasound energy can be directed at cancer cells to heat them and kill them.

ultrasound transducer

A device that produces sound waves that bounce off body tissues and make echoes. The transducer also receives the echoes and sends them to a computer that uses them to create a picture called a sonogram. Transducers (also called probes) come in different shapes and sizes for use in making pictures of different parts of the body. The transducer may be passed over the surface of the body or inserted into an opening such as the rectum or vagina.

ultrasound-guided biopsy (BY-op-see)

A biopsy procedure that uses an ultrasound imaging device to find an abnormal area of tissue and guide its removal for examination under a microscope.

ultraviolet radiation (ul-tra-VYE-o-let ray-dee-AY-shun)

UV radiation. Invisible rays that are part of the energy that comes from the sun. UV radiation also comes from sun lamps and tanning beds. UV radiation can damage the skin and cause melanoma and other types of skin cancer. UV radiation that reaches the Earth's surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation also may add to skin damage that can lead to skin cancer and cause premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter both kinds of UV radiation.

ultraviolet radiation therapy

A form of radiation used in the treatment of cancer.

umbilical cord blood

Blood from the umbilical cord of a newborn baby. This blood contains high concentrations of stem cells (cells from which all blood cells develop).

umbilical cord blood transplantation

The injection of umbilical cord blood to restore an individual's own blood production system suppressed by anticancer drugs, radiation therapy, or both. It is being studied in the treatment of cancer and severe blood disorders such as aplastic anemia. Cord blood contains high concentrations of stem cells needed to produce new blood cells.

uncontrolled study

A clinical study that lacks a comparison (i.e., a control) group.

unconventional cancer treatments

Approaches that use substances or methods of treating cancer that have not been shown to be effective by accepted scientific methods, such as carefully designed clinical trials.

undescended testicles

A condition in which one or both testicles fail to move from the abdomen, where they develop before birth, into the scrotum. Undescended testicles may increase the risk for development of testicular cancer. Also called cryptorchidism.

undifferentiated

A term used to describe cells or tissues that do not have specialized ("mature") structures or functions. Undifferentiated cancer cells often grow and spread quickly.

unilateral

Having to do with one side of the body.

unilateral salpingo-oophorectomy

Surgery to remove the ovary and fallopian tube on one side of the body.

unresectable

Unable to be removed with surgery.

unresectable gallbladder cancer

Cancer that has spread to the tissues around the gallbladder (such as the liver, stomach, pancreas, intestine, or lymph nodes in the area) and cannot be surgically removed.

unresected

Describes an organ, tissue, or cancer that has not been either partly or completely removed by surgery.

unsealed internal radiation therapy

Radiation therapy given by injecting a radioactive substance into the bloodstream or a body cavity, or by swallowing it. This substance is not sealed in a container.

upper GI series

A series of x-rays of the esophagus. The x-ray pictures are taken after the person drinks a solution that contains barium. The barium coats and outlines the esophagus on the x-ray. Also called an esophagram and barium swallow.

urachus (YOU-rah-kus)

A fibrous cord that connects the urinary bladder to the umbilicus (navel). The urachus is formed as the allantoic stalk during fetal development and lasts through life. Also called the median umbilical ligament.

uracil

An anticancer drug that belongs to the family of drugs called alkylating agents.

urea nitrogen

A chemical in the blood produced by the breakdown of protein. Urea nitrogen is removed from the blood by the kidneys. Blood urea nitrogen (BUN) tests are sometimes done to see how well the kidneys are working.

ureter (yoo-REE-ter)

The tube that carries urine from the kidney to the bladder.

ureteronephrectomy

Surgery to remove a kidney and its ureter. Also called nephroureterectomy.

ureteroscopy

An examination of the inside of the kidney and ureter. A thin, lighted tube (called a ureteroscope) is passed through the urethra into the bladder, ureter, and renal pelvis (part of the kidney that collects, holds, and drains urine).

urethra (yoo-REE-thra)

The tube through which urine leaves the body. It empties urine from the bladder.

uric acid

A waste product left over from normal chemical processes in the body and found in the urine and blood. Abnormal buildup of uric acid in the body may cause a condition called gout. Increased levels of uric acid in the blood and urine can be a side effect of chemotherapy or radiation therapy.

urinalysis (YOOR-in-AL-ih-siss)

A test that determines the content of the urine.

urinary (YOOR-in-air-ee)

Having to do with urine or the organs of the body that produce and get rid of urine.

urinary incontinence (YOOR-in-air-ee in-KAHN-tih-nens)

Inability to hold urine in the bladder.

urinary tract (YOOR-in-air-ee)

The organs of the body that produce and discharge urine. These include the kidneys, ureters, bladder, and urethra.

urine (YOOR-in)

Fluid containing water and waste products. Urine is made by the kidneys, stored in the bladder, and leaves the body through the urethra.

urine cytology (YOOR-in si-TOL-uh-jee)

Tests performed on cells in urine to detect disease.

urokinase

A drug that dissolves blood clots or prevents them from forming.

urologic oncologist (yoor-uh-LAHJ-ik on-KOL-o-jist)

A doctor who specializes in treating cancers of the urinary system.

urologist (yoo-RAHL-o-jist)

A doctor who specializes in diseases of the urinary organs in females and the urinary and sex organs in males.

urostomy (yoo-RAHS-toe-mee)

An operation to create an opening from inside the body to the outside, making a new way to pass urine.

urothelium

The lining of the ureters, bladder, and urethra.

ursodiol (ur-so-DYE-ole)

A drug that is used to dissolve gallstones in people who can't have surgery to remove them. It is also being studied in the prevention of colorectal cancer. Ursodiol belongs to the family of drugs called anticholelithics.

uterine cancer (YOO-teh-rin KAN-ser)

Cancer that forms in tissues of the uterus (small, hollow, pear-shaped organ in a woman's pelvis in which a baby grows). Two types of uterine cancer are endometrial cancer (cancer that begins in cells lining the uterus), and uterine sarcoma (a rare cancer that begins in muscle or other tissues in the uterus).

uterine sarcoma (YOO-teh-rin sar-KOH-muh)

A rare type of uterine cancer that forms in muscle or other tissues of the uterus (small, hollow, pear-shaped organ in a woman's pelvis in which a baby grows). It usually occurs after menopause. The two main types are leiomyosarcoma (cancer that begins in smooth muscle cells) and endometrial stromal sarcoma (cancer that begins in connective tissue cells).

uterus (YOO-ter-us)

The small, hollow, pear-shaped organ in a woman's pelvis. This is the organ in which a baby grows. Also called the womb.

UV radiation

Ultraviolet radiation. Invisible rays that are part of the energy that comes from the sun. UV radiation also comes from sun lamps and tanning beds. UV radiation can damage the skin and cause melanoma and other types of skin cancer. UV radiation that reaches the Earth's surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation also may add to skin damage that can lead to skin cancer and cause premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter both kinds of UV radiation.

UVA radiation

A type of ultraviolet (UV) radiation. UV rays are invisible rays that are part of the energy that comes from the sun. UVA radiation also comes from sun lamps and tanning beds. Scientists think that UVA radiation may cause skin damage that can lead to skin cancer and premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter ultraviolet radiation.

UVB radiation

A type of ultraviolet (UV) radiation. UV rays are invisible rays that are part of the energy that comes from the sun. UVB radiation causes sunburn, and scientists have long thought that it can cause melanoma and other types of skin cancer. Skin specialists recommend that people use sunscreens that reflect, absorb, or scatter ultraviolet radiation.

uvula

The soft flap of tissue that hangs down at the back of the mouth (at the edge of the soft palate). Also called palatine uvula.